Applying the denitrification method to 15N and 18O analysis of nitrate in natural groundwater samples

2020 ◽  
Author(s):  
Patricia Stock ◽  
Susanne Roder ◽  
Diana Burghardt
Keyword(s):  
High Accuracy ◽  
The Other ◽  
Free Medium ◽  
Pseudomonas Aureofaciens ◽  
Accuracy And Precision ◽  
Groundwater Samples ◽  
Simplified Method ◽  
Aerobic Cultivation ◽  
Potential Applicability ◽  
Preparation Step

<p>This study aims to develop a simplified denitrification method for the δ<sup>15</sup>N and δ<sup>18</sup>O analysis of nitrate (NO<sub>3</sub><sup>–</sup>) in natural groundwater samples following Zhu et al. (Sci Total Environ. 2018; 633: 1370–1378) and Sigman et al. (Anal Chem. 2001; 73: 4145–4153). With the help of Pseudomonas aureofaciens bacteria, the simplified method induced denitrification of the sample and completely converted the NO<sub>3</sub><sup>– </sup>into measurable N<sub>2</sub>O while avoiding sample fractionation. In contrast to the classic denitrification method (Sigman et al., 2001), which is based on anaerobic cultivation, the bacteria are cultivated aerobically in the simplified method (Zhu et al., 2014). In this study, aerobic cultivation was performed in a nitrate-free medium. Unlike the other two methods, aerobic cultivation was performed without the addition or removal of nitrate in the liquid medium. This eliminates the need for another preparation step, saving time. There was no contamination with external NO<sub>3</sub><sup>–</sup>. After further optimising the influencing factors, the method yielded high accuracy and precision (standard deviations were generally ≤ 0.7‰ for δ<sup>18</sup>O and ≤ 0.3‰ for δ<sup>15</sup>N), confirming the suitability of this procedure. Finally, the potential applicability of the method was demonstrated by measuring the isotopic composition of NO<sub>3</sub><sup>–</sup> in natural groundwater samples.</p>

Simultaneous measurement of two major prostacyclin metabolites in urine

1990 ◽  
Vol 36 (11) ◽  
pp. 1978-1980 ◽  
Author(s):  
S Zureick ◽  
J Nadler ◽  
J Yamamoto ◽  
R Horton
Keyword(s):  
Angiotensin Ii ◽  
Blood Vessels ◽  
Simultaneous Measurement ◽  
Healthy Subjects ◽  
High Accuracy ◽  
High Concentration ◽  
Accuracy And Precision ◽  
Overall Evaluation ◽  
Excretion Rates ◽  
Apparently Healthy

Abstract We describe a combined HPLC-RIA technique to measure both major metabolites of prostacyclin (PGI2): 6-keto PGF1 alpha and 2,3-dinor-6 keto PGF1 alpha. The measurement of the former, which originates from renal blood vessels, and the latter, from systemic vessels and the liver, may provide a better overall evaluation of production than measurement of one metabolite. An aliquot of acidified urine with added 3H-labeled metabolites is adsorbed and then eluted from a C18 Bond-Elut column. The sample is then passed through an HPLC system by use of an isocratic solvent combination that separates the two metabolites from known prostaglandins. The purified metabolites are then quantified by RIA. Using a logit-log10 transform, one can measure between 12 and 250 pg of either metabolite, with high accuracy and precision (CVs of 12% for a low concentration and 7% for a high concentration). Reference values for apparently healthy subjects were, respectively, 107 (SD 45) and 171 (SD 69) ng/g creatinine for 6-keto PGF1 alpha and the dinor metabolite in men (n = 18) and 45 (SD 22) and 141 (SD 28) ng/g creatinine, respectively, in women (n = 15). Indomethacin in standard doses reduced both metabolite values by 50%. Intravenous administration of angiotensin II (5 ng/kg of body wt per minute) did not alter excretion rates, but equipressor doses of norepinephrine (0.1 microgram/kg per minute) increased the production of both metabolites (6-keto greater than dinor).

A comparative study of qualitative immunochemical screening assays for the combined measurement of T-2/HT-2 in cereals and cereal-based products

2011 ◽  
Vol 4 (4) ◽  
pp. 385-394 ◽  
Author(s):  
J. Meneely ◽  
F. Ricci ◽  
S. Vesco ◽  
M. Abouzied ◽  
M. Sulyok ◽  
...  
Keyword(s):  
Sample Preparation ◽  
Low Cost ◽  
Ease Of Use ◽  
The Other ◽  
Accuracy And Precision ◽  
Cost Implications ◽  
Electrochemical Array ◽  
The Cost ◽  
Preparation Techniques ◽  
Speed Of Analysis

Many different immunochemical platforms exist for the screening of naturally occurring contaminants in food from the low cost enzyme linked immunosorbent assays (ELISA) to the expensive instruments such as optical biosensors based on the phenomenon of surface plasmon resonance (SPR). The primary aim of this study was to evaluate and compare a number of these platforms to assess their accuracy and precision when applied to naturally contaminated samples containing HT-2/T-2 mycotoxins. Other important factors considered were the speed of analysis, ease of use (sample preparation techniques and use of the equipment) and ultimately the cost implications. The three screening procedures compared included an SPR biosensor assay, a commercially available ELISA and an enzymelinked immunomagnetic electrochemical array (ELIME array). The qualitative data for all methods demonstrated very good overall agreements with each other, however on comparison with mass spectrometry confirmatory results, the ELISA and SPR assay performed slightly better than the ELIME array, exhibiting an overall agreement of 95.8% compared to 91.7%. Currently, SPR is more costly than the other two platforms and can only be used in the laboratory whereas in theory both the ELISA and ELIME array are portable and can be used in the field, but ultimately this is dependent on the sample preparation techniques employed. Sample preparative techniques varied for all methods evaluated, the ELISA was the most simple to perform followed by that of the SPR method. The ELIME array involved an additional clean-up step thereby increasing both the time and cost of analysis. Therefore in the current format, field use would not be an option for the ELIME array. In relation to speed of analysis, the ELISA outperformed the other methods.

Techniques for Improved Reliability of Wall Thinning Estimation

2006 ◽  
Author(s):  
Yogendra S. Garud
Keyword(s):  
The Other ◽  
Remaining Life ◽  
Data Filtering ◽  
Large Database ◽  
Accelerated Corrosion ◽  
Wall Thinning ◽  
Simplified Method ◽  
Flow Accelerated Corrosion ◽  
The Impact ◽  
Thinning Rate

Wall thinning in pressure retaining components, especially due to the flow-accelerated corrosion, has been a significant factor affecting the safety and unplanned system downtimes. On the other hand, overestimating the impact of possible wall thinning often leads to unnecessary or expensive inspections and replacements. The simplified or quick (short-cut) methods of analysis and prediction often lack the requisite degree of accuracy and confidence. This paper presents a few techniques for better analysis of the wall thinning data to address these issues. These techniques make use of the statistical methods, pattern recognition, and optimization to perform a robust data filtering and thinning rate estimation that accounts for measurement uncertainty. The techniques are discussed with application to a large database and an inspection program. The impact of these analytical improvements is presented in comparison with results of the simplified method of analysis. The results include both the margin on remaining life and the projected wall thinning rates, with implications for inspections.

scholarly journals When regularization gets it wrong: children over-simplify language input only in production

2018 ◽  
Vol 45 (5) ◽  
pp. 1054-1072 ◽  
Author(s):  
Jessica F. SCHWAB ◽  
Casey LEW-WILLIAMS ◽  
Adele E. GOLDBERG
Keyword(s):  
Complex System ◽  
High Accuracy ◽  
Forced Choice ◽  
Choice Task ◽  
The Other ◽  
Natural Languages ◽  
Multiple Factors ◽  
Artificial Languages ◽  
Forced Choice Task ◽  
Unpredictable Variation

AbstractChildren tend to regularize their productions when exposed to artificial languages, an advantageous response to unpredictable variation. But generalizations in natural languages are typically conditioned by factors that children ultimately learn. In two experiments, adult and six-year-old learners witnessed two novel classifiers, probabilistically conditioned by semantics. Whereas adults displayed high accuracy in their productions – applying the semantic criteria to familiar and novel items – children were oblivious to the semantic conditioning. Instead, children regularized their productions, over-relying on only one classifier. However, in a two-alternative forced-choice task, children's performance revealed greater respect for the system's complexity: they selected both classifiers equally, without bias toward one or the other, and displayed better accuracy on familiar items. Given that natural languages are conditioned by multiple factors that children successfully learn, we suggest that their tendency to simplify in production stems from retrieval difficulty when a complex system has not yet been fully learned.

scholarly journals Advancing System Performance with Redundancy: From Biological to Artificial Designs

2019 ◽  
Vol 31 (3) ◽  
pp. 555-573 ◽  
Author(s):  
Anh Tuan Nguyen ◽  
Jian Xu ◽  
Diu Khue Luu ◽  
Qi Zhao ◽  
Zhi Yang
Keyword(s):  
Neural Network ◽  
System Performance ◽  
Human Vision ◽  
The Other ◽  
Superior Performance ◽  
Fundamental Characteristic ◽  
Unified Theory ◽  
Biological Processes ◽  
Accuracy And Precision ◽  
Similar Operation

Redundancy is a fundamental characteristic of many biological processes such as those in the genetic, visual, muscular, and nervous systems, yet its driven mechanism has not been fully comprehended. Until recently, the only understanding of redundancy is as a mean to attain fault tolerance, which is reflected in the design of many man-made systems. On the contrary, our previous work on redundant sensing (RS) has demonstrated an example where redundancy can be engineered solely for enhancing accuracy and precision. The design was inspired by the binocular structure of human vision, which we believe may share a similar operation. In this letter, we present a unified theory describing how such utilization of redundancy is feasible through two complementary mechanisms: representational redundancy (RPR) and entangled redundancy (ETR). We also point out two additional examples where our new understanding of redundancy can be applied to justify a system's superior performance. One is the human musculoskeletal system (HMS), a biological instance, and the other is the deep residual neural network (ResNet), an artificial counterpart. We envision that our theory would provide a framework for the future development of bio-inspired redundant artificial systems, as well as assist studies of the fundamental mechanisms governing various biological processes.

Apply Language Nature Rhythm to Large Scale Duplicated Text Detection

2012 ◽  
Vol 457-458 ◽  
pp. 635-640
Author(s):  
Fan Chen ◽  
Zhi Yong Feng ◽  
Geng Zhao
Keyword(s):  
Large Scale ◽  
High Accuracy ◽  
Text Detection ◽  
The Other ◽  
Duplication Detection ◽  
The Web

It is urgent that detect the duplication in large scale text in the Web. An arithmetic based on language rhythm for text duplication detection is proposed here. Get the nature rhythm marked by punctuations in text and build the rhythm compare matrix to complete the publication detection for each paragraph. This arithmetic is different with the other one which is based on words analysis. And it has a high accuracy and a low complicacy.

Development of Flexible Worktable for Endmilling Based on Parallel Mechanism

2010 ◽  
Vol 447-448 ◽  
pp. 826-830 ◽  
Author(s):  
Tomohisa Tanaka ◽  
Masahiro Komori ◽  
Jiang Zhu ◽  
Yoshio Saito
Keyword(s):  
Machine Tools ◽  
Parallel Mechanism ◽  
High Accuracy ◽  
The Other ◽  
Geometrical Parameters ◽  
Basic Design ◽  
Positioning Accuracy ◽  
Accuracy Measurement ◽  
High Degree ◽  
Work Table

Parallel mechanism has many advantages, such as high stiffness, high accuracy, high degree of freedom (DOF), etc. These fine features are suitable for work table of machine tools for production of recent complicated designs. In this study, six axes linear-actuated parallel mechanism was chosen as the basic design for work table. First, geometrical parameters of the table were designed to satisfy the required movable range with minimum cutting load. Then, the work table was actually constructed and its performance was evaluated. From positioning accuracy measurement, it was found that the table is suitable to be used for machining of complicated products. On the other hand, from actual cutting tests of primitive shapes using chemical wood and measurement of the machined shapes, potential of the table for real cutting application was confirmed.

scholarly journals Expanding NIST Calibration of Fluorescent Microspheres for Flow Cytometry to More Fluorescence Channels and Smaller Particles

Materials ◽  
2020 ◽  
Vol 13 (18) ◽  
pp. 4111
Author(s):  
Paul DeRose ◽  
Linhua Tian ◽  
Elzafir Elsheikh ◽  
Aaron Urbas ◽  
Yu-Zhong Zhang ◽  
...  
Keyword(s):  
Flow Cytometry ◽  
Living Cells ◽  
High Accuracy ◽  
Flow Cytometer ◽  
National Institutes Of Health ◽  
Fluorescent Microspheres ◽  
Accuracy And Precision ◽  
Working Together

The National Institute of Standards and Technology (NIST), the National Institutes of Health (NIH) and other industry stakeholders have been working together to enable fluorescence intensities of flow cytometer calibration beads to be assigned quantitative equivalent reference fluorophore (ERF) values with high accuracy and precision. The ultimate goal of this effort is to accurately quantify the number of antibodies bound to individual living cells. The expansion of this effort to assign ERF values to more than 50 fluorescence channels and particles with diameters ranging from 10 μm down to 80 nm is reported here.

scholarly journals Multimode Detections from Surveys

2000 ◽  
Vol 175 ◽  
pp. 192-204
Author(s):  
C. Aerts
Keyword(s):  
High Accuracy ◽  
The Other ◽  
Time Base ◽  
Be Stars ◽  
Preliminary Results ◽  
Other Hand ◽  
Multiple Frequencies

AbstractIn this study we present an overview of the search for multiple frequencies in variable Be stars from surveys. We review the recent ground-based photometric surveys and conclude from them that multiperiodicity is not detected. The photometric experiment on board Hipparcos, on the other hand, does allow us to derive multiple periods for a few Be stars. We present the results of our frequency searches in the Hipparcos data for 50 λ Eri stars.Further we review the recent spectroscopic campaigns dedicated to some stars. It seems that all of these campaigns point to multiperiodic phenomena, although for most of them the time base is insufficient to derive the periods with high accuracy. Moreover, the spectroscopic periods are often not the same as those found from the photometry. This clearly demonstrates the necessity of long-term simultaneous photometric and spectroscopic campaigns. We present the preliminary results of such a campaign for the λ Eri star HD 105382.We close with reflections on the cause of the variability observed in the λ Eri stars and on the best viewpoint for further research in this area.

Sign in / Sign up

Export Citation Format

Share Document